Single-crystal growth and structure determination of misfit layer oxide [Sr₂TlO₃][CoO₂]_1.77

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• 作者：Markus Valkeapä ; ä ; Martin Valldor ; Sven Lidin ; Tomasz Lada ; Andrzej Morawski ; Sten Eriksson
• 关键词：A1. Crystal structure ; A1. X-ray diffraction ; A2. Growth at high pressure ; A2. Growth from melt ; A2. Single-crystal growth ; B1. Misfit layer compounds ; B1. Oxides
• 刊名：Journal of Crystal Growth
• 出版年：2007
• 出版时间：1 August 2007
• 年：2007
• 卷：306
• 期：1
• 页码：233-239
• 全文大小：645 K

文摘

We have synthesized single crystals of the misfit layer cobaltate [Sr₂TlO₃][CoO₂]_1.77 and determined its crystal structure by the means of X-ray single-crystal diffraction (XRSD) and transmission electron microscopy. The synthesis took place by spontaneous crystallization from an oxide melt at high gaseous pressure. The structure is described by two monoclinic subsystems, which share the unit cell parameters, a=4.933(5) Å, c=11.470(12) Å, and β=98.00(10)°, but are incommensurate in the direction of b-axes: b₁=5.009(8) Å and b₂=2.830(8) Å, where b₁ is for the subsystem [Sr₂TlO₃] and b₂ for [CoO₂]. The layer sequence in the structure consists of CdI₂-type structured (CoO₂)_∞ and three puckered rock-salt (RS) layers, two of which are (SrO)_∞ and one (TlO)_∞. The solved structure confirms that the thermoelectric compounds [Ca₂CoO₃][CoO₂]_1.62 (Co-121) and [Sr₂TlO₃][CoO₂]_1.77 (Tl-121) are isostructural.